The full error message is:
Exception: java.lang.Exception: Version mismatch detection error flsx.jar/flsx.dll.
Please ensure these files are matched [dll=4.7.1 jar=4.7.2]
This is a known issue with release 4.7.2 of the Signature SDK for Windows when used with 64-bit Java.
As at the time of writing (Jun 2023) the workaround for this is to install an older version of the SDK such as 4.7.1 which can be obtained from Box here:
Please note that the above link is only valid for 60 days, i.e. until Aug 25th 2023.
After that there are 2 options:
1. Check the SDK download page under "For signature" at https://developer.wacom.com/en-us/developer-dashboard/downloads to see if a newer release has become available.
2. Click the "Submit a request" link at the top of this page to request a replacement Box link.